In Patent Literature 1, there is disclosed a wire reel for a reinforcing bar binding machine. The reinforcing bar binding machine is configured to include a housing chamber provided in a reinforcing bar binding machine body and a wire reel mounted in the housing chamber to wind a wire for binding a reinforcing bar, whereby the wire is fed out with a rotation of the wire reel and the wire is twisted after being wound around the reinforcing bar to bind the the reinforcing bar. The wire reel is made of plastic such as an ABS resin, polyethylene, or polypropylene, in which a cylindrical hub with the wire wound thereon and a pair of flanges provided on both sides in an axis direction of the hub are integrally formed.
As the wire used in the reinforcing bar binding machine, there are various types such as wires different in material, wires different in size such as a diagram, and wires different in shape such as a single wire, a double wire, a strand wire, a bare wire, and a covered wire. These wires are used differently according to its application. Therefore, many kinds of information (a plurality of transmission holes) are provided inside the hub of the wire reel to identify the type of the wire (or the type of the wire reel (meaning which type of a wire reel is wound with which type of a wire)). The type of the wire can be identified through the information. Specifically, the number and the position of the transmission holes are previously set according to the type of the wire. The type of the wire can be identified by confirming the number and the position of these transmission holes.